Transmission-equalization arrangement



Filed Dec. 23 1920 r T' H INVENTOR ATTORNEY Patented Feb. 19,1924.

gineers, in an article entitle LE0 H. DABBOW, or'BRooKLY N,

n TELEGRAPH COMPANY,

o s'm'r NEW YORK,

AMERICAN 'rnnnrnonn A conroaarron or new Your.

ASSIGN OR TO TRANSMISSION-EQUALIZATION ARRANGEMENT.

Application filed December as,

T 0 all whom it may concern:

H. DARROW,

Be it known t at 1, Leo residing at Brooklyn, in the countyp Kings and State of New York, have 1nvented certain Improvements in Transmission-Equalization Arrangements of which the following is a specification.

This invention relates to transmission lines and particularly to'arrangements or equalizing transmission over suc lines when such'lines possess difierent electrical characteristics. I The arrangements of the invention are particularly applicable to a link or cord, circuit which is used to establis connections with a. plurality of subscribers lines. As the subscribers lines might be of different lengths and different electrical characteristics, it is apparent that the source of current supply in former types of in circuits would vfurnish varying amounts of current over the various lines-and this give variable transmission, the transmission being better over the shorter lines than over the longer lines ordinarily. In general it is the object of the invention to overcome this difiiculty and to provide arrangements which will insure equal transmission over the various types 0 lines. Other objects and purposes of the invention will appear more fully from the detailed description hereinafter given. 1

The objects of this invention are accomplished by including in the talking current supply circuit of the link or cord circuit, by which connections are established with difierent subscribers lines, a vacuum tube device so connecte into the circuit that it possesses for the purposes of this invention the characteristic of negative resistance. A complete description of a vacuum tube device arranged so that it possesses the characteristic of a negative resistance may be found in volume 6, 1918, Proceedings of the Institute of Radio End The dynatron, a vacuum tube possessinlg electric resistance, A. W. ull, pages 5 35. It is evident that if a negative resistance of proper value is connected in series in the current supply circuit of the link circuit, the positive resistance of the line to which the link circuit is connected will neutralize a certain amount of the ne ative resistance in series with the source 0 ourf than to the k in any way 10 be calle .trated a negative 1920. Serial No. 432,835.

This will allow a greater curiurnished to the longer lines shorter ones current supply thus obtained on the longer rent supply. rent to be lines will make up for the greater losses whic I this manner transmission over lines of difiering electrical characteristics may substantially constant. A device possessing the above mentioned characteristics of negative resistance may be broadly defined as one through which an increase of current is accompanied by a decrease of potential difand the greater hoo ference between the terminals, or vice versa.

In other words, let E be the potential difference between the terminals of the converting device; let I bethe corresponding current flowin through the converting device; assume t at the current I be changed an amount representedby '61; this will cause a corresponding change in the potential difierence which may 8E. As is usual, .also, if an increase of current or potential is considered positive, then a decrease in either must be considered negative; then the converting device must of such a character that the ratio 8E/ 81 is negative. When such is'the case, it may properly be said to have the roperties of negative resistances.

T e invention may be more fully understood from the following description of the accompanying drawin in w ic ris illuspreferred em odiment of the invention and from the description of its operation. In the drawingis sh ink,

and windings of the repeating with batas shown, through which the talking current tion is furnished to the'subscribers loop. 'Amociated with the plug Ppis the relay 5 when the plug subscribers' line, the filament circuit of the vacuum it operative. 5 also renders operative over conthe supervisory lamp is, inserte The relay ductor 9 a circuit for circuit, terminating in the plugz and serves for the connecthe supervisory lamp l2,

- t e sleeve vacuum tuhev device to function.

. ing coil '1.

lamp 10 is controlled by the relay 3 included in the talking current supply circuit. The three-element vacuum tu e device when. connected in the munner shown is in itself trical energy Accordingly, there is inserted in the talking supply circuit a network N of 'suchimpedance characteristics that it will prevent the generation of continuous oscillations, and cause what is commonly termed singing to take place in the talking circuit. Associated and winding of repeatin coil 1 is apparatus similar to that already described with. respect to the leftdiand winding of repeatssociated with plug P is relay 6, which controls the filament circuit of the three-element vacuum tube device A In the talking supply circuit is supervisory relay 4-, which controls the operation of and also net 10. The supervisory work h The operation of lows: line, such I the plug P circuit of the jack of the line sleeve contact of plug over conductor 7, winding of relay 5, to battery and ground, thereby operating relay 5.- I close at its right-hand contact the normally open filament circuit of the vacuum tube device A.,. This will cause the filament to heat to incandescence, and will cause the Talking current will then be supplied through the vacuum tube device relay 3, network N and the left-hand win ings of coil 1 over the talkin conductors of the plug 1%, and the jack of the line, and thence over the talking conductors of the line. If the line uppens to be a relatively long line, it will lave a. relatively large resistance which will neutralize a relatively large'amount of the negative resistance of the vacuum tube device and allow a relatively large current for talking purposes to be supplied to the subscribers line. Conversely, if the line with e source of elec-,

with the righth The relay 5will;

cord, contacts of d with which connection is established neeaeac which connection is. established happens to be a relatively short line, it will have a relatively small resistance and will neutralize a. relatively small amount of the negative resistance of t e vacuum tube device. This will allow a smaller talking battery sup to be furnished to the subscribers line than in long subscrihers line. tery supply which will be 1 longer loops will compensate tiali constant. While the invention has been disclosed as embodied in certain specifi acteristic of negative electrical resistance whereby transmission over said lines may be maintained substantially constant.

2. A link circuit adapted for establishing connections withs-ubscribers lines of dill-ering electrical characteristics, lE'OHIPBZli) sup-- ply circuit included in said link circuit for supplying direct current over said lines to the subscribers stations, and a vacuum tube 4 in said current supply circuit which, when connected in series with at relatively large resistance, will allow a lar er current to be tran mitted therethrough than when connected in series with a smaller resistance.

In testimony whereof, I have signed my name to this specification this 18th day of December 1920.

the case where connection is made to a Lee H. nsnn ow. i 

